On Wed, 2014-09-10 at 13:14 -0700, H. Peter Anvin wrote: > On 09/10/2014 12:30 PM, Toshi Kani wrote: > > > > When WT is unavailable due to the PAT errata, it does not fail but gets > > redirected to UC-. Similarly, when PAT is disabled, WT gets redirected > > to UC- as well. > > > > But on pre-PAT hardware you can still do WT. Yes, if we manipulates the bits directly, but such code is no longer allowed for PAT systems. The PAT-based kernel interfaces won't work for pre-PAT systems, and therefore requests are redirected to UC- on such systems. Thanks, -Toshi -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>